To diagnose the excitation processes of the brain, typically stimulation techniques like continuous excitation, multiple single excitations and periodic excitations or stimulations have been used. For continuous stimulation, for example, continuous sound or visual patterns are considered. Individual excitations result for example in so-called acoustic or visually evoked potentials. As periodic excitation, a stimulation with flickering light can be used, for example, to diagnose a photosensitive epilepsy. Based for example on excitation responses of the brain or the sense organs as measured by means of electrodes and the psychophysical findings (for example the number of recognized patterns or heard sounds) conclusions can be drawn as to the functioning of the sensory system explored.
In biofeedback training, optical or acoustic feedback effects are therapeutically used to bring about in the patient a voluntary control of some action of the patient's bodily function, especially the sympathetic nervous system, in a desired manner. The feedback signals enable, therefore, a self-control and increase the influence upon the bodily function which pertains by the patient. Applications of biofeedback training for example include applications in functional heart conditions and neuromuscular stress states. With previous diagnostic methods, the dependency between excitation responses and the particular activity were not explored in detail. Only a relatively few parameters of cerebral activity were investigated. With the standard process it is not possible to match the stimulation to the specific rhythmic brain activity of individual patients so as to be able to detect significantly more functional and response ranges. It is especially not possible to investigate the effect of targeted manipulations in rhythmic cerebral brain activity in different frequency regions (for example their amplitude damping) and different brain areas on information processing.
It is a prerequisite of biofeedback training that the patient voluntarily and willingly desires the improved bodily function and participates therein. With most of the organ systems of the body and for many brain functions this is not the case however or is not the case to a sufficient degree. Difficulties are encountered when the patient has a cerebral disorder, for example, is a neglected patient following a brain infarct or has some other illness or medical condition following an illness which interferes with understanding or recognition and which disables a voluntary effect even on simple bodily functions, makes them more difficult or even impossible. Thus neglect patients whose body parts no longer respond can be scarcely responsive to biofeedback training at least with respect to the body parts which are nonresponsive.